Biplane wing for aircraft



Aug. 11, 1925. 1,549,079

H. P. FOLLAND ET AL BIPLANE WING FOR AIRCRAFT Filed Nov. 17, 1924 Patented Aug. 11, 1925.

HENRY rnrLLiP EoLLAND AND HENRY EDWARD PRESTON, or OHELTENHAM', ENG- LAND, AssreNoRs T THEMSELVES AND THE GLOUCESTER-SHIRE AIRCRAFT comrANY, LIMITED, 0E CHELTE-NHAM, ENGLAND.

BIPLANE WING FOR AIRCRAFT.

Application filed November 17, 1924. Serial No. 750,401.

To all whom it may concern:

Be it known that we. HENRY PHILLIP FoLLAND and HENRY EDWARi) PREs'roN, subjects of the King of Great Britain, residing at Sunningend Works, Cheltenham, England, have invented a new and useful Improvement in Biplane Vvings for Aircraft, of which the following is a specification.

This invention relates to improvements in biplane wings for aircraft.

The main object of our invention is to provide biplane wings of increased efficiency whereby the weight and dimensions thereof can be reduced and the stability, controllability and performance of the aircraft improved.

According to our invention the top plane is arranged with a thick high lift section, while the bottom plane has a comparatively normal section.

Preferably the thickness of the top plane is reduced at or towards the centre in the region of the propeller slipstream and the angle of incidence is also made smaller at this point to avoid some interference with the body of the machine. The reduced thickness at the centre of the plane also reduces the adverse effect on the tail of the machine which would occur if the plane were of thick section at this point.

The outer ends of the top plane are preferably also tapered in thickness for a distance of about one fifth of the total span. This taper permits of the most economical weight of construction and also gives the best efficiency for the ends of the high lift plane. The taper tip may also be arranged with a slightly reduced incidence towards the tip. The object of this is to prevent the tip of the plane losing its lift or stalling before the main portion of the plane. The reduced incidence at the centre of the plane also gives this advantage.

In order to obtain improved lateral control, the ailerons on the top plane are arranged with a small chord at the inner end and increasing towards the tip.

In the accompanying drawings, which illustrate the invention, Figure 1 is a side elevation, Figure 2 a front elevation, Figure 3 a plan of the top plane (Figures 1 and 2), Figure 4 a section on the line iv-4L Figure 3, Figure 5 a section on the line 55 Figure 3, and Figure 6 an end elevation of the plane shown in Figure 3, Figures 4:, 5 and 6 being to a larger scale. Figure 7 is a front elevation of a modification, and

Figure 8 is a section of a plane.

Referring to Figure 8, this is given to 1llustrate and define the meaning of the words thick high lift section and normal section. A plane of thick high lift section 18 one in'which the height of its top surface X is approximately from, say 8.5% to 20% of its chord length Y. A plane of normal section is one in which the height of its top surface X is less than, say, 8.5% of its chord length Y. In all cases the difference between a plane of thick high lift section and normal section is 2% or more.

Referring now to Figures 1 to 6, 1 and 2 are the top and bottom planes respectively of an aeroplane having a body 3, landing chassis 4; and tractor screw 5 of ordinary construction. The top plane between the tip and its central portion is of thick high lift section, while the thickness of the plane is reduced towards the centre in the region of the propeller slipstream. The angle of incidence of this portion of the plane is also made smaller at this point to avoid interference with the body of the machine, as is shown in Figure 4E.

The outer ends of the top plane are also tapered in thickness for about one fifth of the total span, as shown in Figure 2, the tapered tip being arranged with a slightly reduced incidence, as shown in Figure 6.

6 are ailerons having a small chord at the inner end and increasing towards the tip, as shown in Figure 8.

The bottom plane 2 is of normal section.

Referring now to Figure 7, the top plane 1 is of thick high lift section, except at the tips which are tapered in thickness for a distance of about one fifth of the total span, while the bottom plane is of normal section.

What we claim is 1. A biplane in which the top plane is of highlift section, having the height of its top surface from 8.5 percent to 20 percent of its chord length, and a bottom plane of normal section in which the height is less than 8.5 percent of its chord section,

Ni 'FFICIE. 1

the ends of the top plane being tapered outwardly for about one-fifth of the total span.

2. A biplane in which the top plane is of high lift section having the height of its topsurface from 8L5 percent to 20 percent of its chord length, and a bottom plane of normal section in which the height is less than 8.5 percent of its chord section, the

ends of the top plane being tapered out- 10 wardly for about one-fifth of the total span, and being reduced in incidence toward the top.

In testimony that we claim the foregoing as our invention we have signed our names 15 thistenth day of July, 1924:- V

HENRY PHILLIP FOLLAND. HENRY EDWARD PRESTON. 

